Man page - atanhl(3)

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Manual

atanh

NAME
LIBRARY
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
ATTRIBUTES
STANDARDS
HISTORY
BUGS
SEE ALSO

NAME

atanh, atanhf, atanhl - inverse hyperbolic tangent function

LIBRARY

Math library ( libm , -lm )

SYNOPSIS

#include <math.h>

double atanh(double x );
float atanhf(float x );
long double atanhl(long double x );

Feature Test Macro Requirements for glibc (see feature_test_macros (7)):

atanh ():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| _XOPEN_SOURCE >= 500
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

atanhf (), atanhl ():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

These functions calculate the inverse hyperbolic tangent of x ; that is the value whose hyperbolic tangent is x .

RETURN VALUE

On success, these functions return the inverse hyperbolic tangent of x .

If x is a NaN, a NaN is returned.

If x is +0 (-0), +0 (-0) is returned.

If x is +1 or -1, a pole error occurs, and the functions return HUGE_VAL , HUGE_VALF , or HUGE_VALL , respectively, with the mathematically correct sign.

If the absolute value of x is greater than 1, a domain error occurs, and a NaN is returned.

ERRORS

See math_error (7) for information on how to determine whether an error has occurred when calling these functions.

The following errors can occur:
Domain error: x less than -1 or greater than +1

errno is set to EDOM . An invalid floating-point exception ( FE_INVALID ) is raised.

Pole error: x is +1 or -1

errno is set to ERANGE (but see BUGS). A divide-by-zero floating-point exception ( FE_DIVBYZERO ) is raised.

ATTRIBUTES

For an explanation of the terms used in this section, see attributes (7).

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STANDARDS

C11, POSIX.1-2008.

HISTORY

C99, POSIX.1-2001.

The variant returning double also conforms to SVr4, 4.3BSD.

BUGS

In glibc 2.9 and earlier, when a pole error occurs, errno is set to EDOM instead of the POSIX-mandated ERANGE . Since glibc 2.10, glibc does the right thing.

SEE ALSO

acosh (3), asinh (3), catanh (3), cosh (3), sinh (3), tanh (3)